A Lab Aloft: The Advantage of Laboratory Time in
Space
Guest blogger Dr.
Mark Weislogel shares his thoughts on the advantages of working long-duration
investigations on the International Space Station.
By engaging in long-duration
investigations, there is time to think things over and, when unexpected events
occur, there is time to respond in a creative and curious way.
Time, resources and
astronaut involvement factor into the success of long-duration investigations
on the station.
June 2013 – The second set of Interior Corner Flow (ICF) vessels (ICF3, ICF5, ICF6, ICF7, and ICF8) were launched on board the ATV-4 on June 5, 2013. Operations on board the ISS are continuing for the first set on CFE-2 vessels ICF4 and ICF9.
November 2012 – The first set of ICF vessels (ICF4
and ICF9) were launched on SpaceX-1 on October 7, 2012, then transferred
to the ISS. The next set of five ICF vessels (ICF3, ICF5,
ICF6, ICF7 and ICF8) are currently going through environmental
testing on the ground in preparation for flight and are scheduled
to launch on ATV-4 in April 2013.
October
2012 –The next set of ICF vessels (ICF4 and ICF9)
are tentatively scheduled to launch on SpaceX-1. Five additional
ICF vessels (ICF3, ICF5, ICF6, ICF7, and ICF8) are tentatively scheduled
to launch on SpaceX-2 at the end of 2012. Each ICF vessel
is uniquely designed to explore the effect of the vessel geometry
on interior corner wetting in microgravity.
Status
May
to June 2012 – The final two scheduled Vane Gap 2 (VG2)
unfilled perforations tests were completed. Don Pettit
completed a test on May 10, 2012, and Joe Acaba completed the second
test on June 13, 2012. Both Don and Joe were able to find all
four critical wetting angles. All scheduled unfilled perforation
tests have been completed for VG2.
May 2012 – Astronaut
crew training was held for Capillary Flow Experiments 2 (CFE-2) flight experiments
on April 30 and May 1 at NASA JSC. Astronauts Chris Cassidy (Increments
35-36) and Karen Nyberg (Increments 36-37) were trained with the CFE-2 ICF4 and
ICF9 trainer units, including installation on a Maintenance Work Area (MWA) in
a mockup of the ISS LAB module. CFE-2 training was performed by Chuck Bunnell
(ZIN). The CFE-2 PI, Mark Weislogel attended and provided
a science overview for the CFE-2 experiment.
March
29, 2012 – A
Systems Acceptance Review (SAR-1) was held for ICF4 and ICF9 to
verify the hardware is ready for flight. The ICF4 and ICF9
hardware passed the SAR-1 review and are being prepared for flight
on SpaceX-1.
January to March
2012 – Increment 30 commander, Dan Burbank, and flight
engineer, Don Pettit, completed a series of vane gap tests with
filled (VG1) and unfilled (VG2) vane perforations to determine critical
wetting angles. An extra
science test was also completed using the ICF1 vessel. All
test matrices and extra science runs have been completed for VG1
and ICF1.
January 26,
2012 – Astronauts
Sunita Williams, Tom Marshburn, and Kevin Ford were trained on installation
of CFE-2 units on the Maintenance Work Area (MWA) and CFE-2 science
operations. Oct. 7, 2011 – Increment 29 commander,
Mike Fossum performed a Filled Perforations test of VG1 investigating
the critical angles in quadrants 3 and 4. Observed the same
bulk shift phenomena initially observed during the Sept. 15 test.
Sept. 30, 2011 – Increment 29 commander, Mike Fossum
performed the VG2 initial “Dry Chamber” test and found
the expected critical angles within 3-4 deg of predictions.
Sept 15, 2011 – Increment 28 flight engineer, Mike
Fossum performed the first Filled Perforations test of VG1 investigating
the critical angles in quadrants 1 and 2. Observed a bulk
shift phenomena, i.e. movement of fluid from one side of vane to
the other at base of test chamber.
May 3, 2011 – The ISS flight engineer
Ron Garan operated the CFE-2 Interior Corner Flow2 (ICF2) vessel
in the US Lab on the Maintenance Work Area (MWA). The
test operation consisted of two compressed bubble tests in the transport
tube of the ICF2 vessel. The Principal Investigator, Mark Weislogel
was at the NASA Glenn Research Center to observe and direct operations
from the Telescience Support Center.
January 18,
2011 – Cady Coleman completed 3 test
runs on the CFE-2 Interior Corner Flow2 (ICF2). This series
of tests were performed with ICF2 to test capillary flow with bubbles
in the test fluid.
December 2010 - Capillary Flow Experiment-2 (CFE) Vane
Gap-1 operated on ISS. The CFE Van Gap-1 (VG-1) module was
operated for a fourth time by Increment 25 astronaut Scott Kelly
on Wednesday, December 8, 2010.
September 29, 2010 – The
CFE-2 experiment launched 4 test vessels on STS-131/Flight 19A in
April 2010. On September 7, 2010 the CFE-2 experiment was set up
in the Japanese Experiment Module and operated by crewmember Shannon
Walker. To date CFE-2 has completed 11 of 16 Interior Corner Flow
1 (ICF1) test points.
Capillary Flow Experiment - NASA astronaut
Scott Kelly, Expedition 26 commander, works on the hardware setup
for a Capillary Flow Experiment (CFE) Vane Gap-1 experiment. The
CFE is positioned on the Maintenance Work Area in the Destiny
laboratory of the International Space Station. CFE observes the
flow of fluid, in particular capillary phenomena, in microgravity.
Astronaut Don Petit demonstrates how to use a cup he made from
a piece of transparency paper. The unique shape allows him to
drink his coffee in zero gravity without having to suck it from
a bag.
• Capillary Flow Experiments
(CFE-2) consists of eleven approximately 1 to 2 kg test vessels
designed to probe certain capillary phenomena of fundamental and
applied importance, such as: capillary flow in complex containers,
critical wetting in discontinuous structures and surfaces, and passive
gas-liquid phase separations. Quantitative video images from the
simply-performed flight experiment crew procedures will provide
immediate confirmation of the usefulness of current analytical design
tools, as well as provide guidance to the development of new ones.
• Vane Gap experiments investigate a fundamental, geometric critical
wetting condition that occurs in complex systems where one or more
substrates are porous (i.e. screens or perforated plates). The experiments
determine both dynamic wetting and equilibrium interface behavior.
• Interior Corner Flow experiment quantifies the nature of large
length scale capillary flows and bubbly capillary flows throughout
3-dimensional polygonal containers for the purpose of theory development,
verification, a demonstration of passive phase separation.
Capillary Flow Experiments (CFE)
Status
The CFE experiment was completed in November
2007 and all 6 CFE units were returned. CFE was operated 19 times
over Increments 9-16 (August 2004 thru November 2007), exceeding the
original test matrix of 6 planned operations. The experiment utilized
55+ crew hours and 7 different astronauts have operated CFE (M. Fincke,
W. McArthur, J. Williams, M. Lopez-Alegria, S. Williams, C. Anderson,
P. Whitson). Approximately 39 hours of video data were recorded and
downlinked, and included over 700 individual test points. Over fifteen
invited, published and other technical presentations on the CFE status
and results have been made to date. Two journal articles have been
published and a third is in preparation.
Overview
The Capillary Flow Experiments
(CFE) are a suite of fluid physics flight experiments designed to
investigate large length scale capillary flows and phenomena in
low gravity. The CFE data to be obtained will be crucial to the
Space Exploration Initiative, particularly as it pertains to fluids
management systems such as fuels and cryogen storage systems, water
collection and recycling, thermal control systems, and materials
processing in the liquid state. NASA’s current plans
for exploration missions assume the use of larger liquid propellant
masses than have ever flown on interplanetary missions. Under low-gravity
conditions, capillary forces can be exploited to control fluid orientation
so that such large mission-critical systems perform more reliably.
CFE is a simple fundamental
scientific study that can yield quantitative results from safe,
low-cost, short time-to-flight, handheld fluids experiments. The
experiments aim to provide results of critical interest to the capillary
flow community that cannot be achieved in ground-based tests such
as tests to probe dynamic effects associated with a movingcontact
boundary condition, capillary-driven flows in interior corner networks,
and critical wetting phenomena in complex geometries. Specific applications
of the results center on particular fluids challenges concerning
propellant tanks. The knowledge gained will help spacecraft fluid
systems designers increase system reliability, decrease system mass,
and reduce overall system complexity.
CFE encompasses three experiments with two unique experimental units
per experiment. There are multiple tests per experiment. Each of the
experiments employs parametric ranges and test cell dimensions that
cannot be achieved in groundbased experiments. All units use similar
fluid injection hardware, have simple and similarly sized test chambers,
and rely solely on video for highly quantitative data. Silicone oil
will be used for these tests. Differences between units are primarily
fluid properties, wetting conditions, and test cell geometry. The
experiment procedures are simple and intuitive.
CFE
Interior
–ICF
Spontaneous capillary flows in containers of increasing complexity
have been designed to determine important transients for low-g propellant
management. Significant progress has been made for complex containers
that are cylindrical, but many practical systems involve containers
with geometries that are tapered.
The taper of the irregular polygonal cross section of the test cells
provides particular design advantages in preferentially locating the
liquid where desired. Passive capillary flow in such containers is
called imbibition and cannot be tested on the ground for large three-dimensional
geometries with “underdamped fluids”—a most common
characteristic of low-g fluids systems. The equations governing the
process are known but have not been solved analytically to date because
of a lack of experimental data identifying the appropriate boundary
conditions for the flow problem. Experimental results will guide the
analysis by providing the necessary boundary condition(s) as a function
of container cross section and fill fraction. The benchmarked theory
can then be used to design and analyze capillary devices such as three-dimensional
vane networks and tapered screen galleries for bubble-free collection
and positioning of fuels for satellites, an important and outstanding
problem for propellant management aboard spacecraft.
CFE
Vane
–VG
A complicated critical wetting condition arises between interior corners
that do not actually contact; such as in the gap formed by a vane
and tank wall of a large propellant storage tank (a commonality in
practice), or near the intersection of vanes in a tank with complex
vane network. Two CFE units will be employed to investigate this phenomenon
using a right cylinder with elliptic cross section with a single central
vane that does not contact the container walls.
The vane can be pivoted varying the angle between the vane and the
wall and also varying the size of the vane-wall gap. The vane is slightly
asymmetric so that two gaps can be tested for each container. All
static interface shapes recorded by video will be compared quantitatively
with shapes computed using a computer algorithm. A major goal of this
experiment is to carefully observe all interface configurations during
the rotation of the vane and to test the repeatability and reversibility
of the critical wetting phenomena.
CFE
Contact
–CL
Two CFE units will be used to study a fundamental and practical concern
for low-g fluid phenomena—the impact of the dynamic contact
line. The contact line controls the interface shape, stability, and
dynamics of capillary systems in low g. The CFE–CL experiments
will provide a direct measure of the extremes in behavior expected
from an assumption of either the free or pinned contact line condition.
The two units are identical except for their respective wetting characteristics.
Status
The CL–1, the ICF, and VG units are complete and awaiting launch.
CFE–CL unit 2 (CL–2) was launched to the International
Space Station (ISS) on Progress 13 in January 2004. ISS Science Officer
Michael Fincke, operated the CL–2 unit on August 28 and again
on September 18, 2004. CL–2 operations were also performed on
December 20, 2005 and on April 18, 2006 by ISS Science Officers, William
McArthur and Jeff Williams, respectively. Video data was taken and
is currently being analyzed. Tests include a variety of fluid disturbances,
such as tap, slide, multiple slide, push, swirl, and axial perturbations.
Preliminary results were recently reported1 where it has been observed
that the correct contact line boundary condition is pivotal to accurate
modeling of large length scale capillary surface dynamics. In addition,
it was observed how large amplitude multiple slide disturbances act
to form ‘hourglass’ configurations in the smooth cylinder
while the surface remains pinned in the pinning cylinder. Axial mode
drop ejection tests were performed and obvious differences in settling
time and natural frequency as a function of contact line condition
and disturbance type were observed. Publication of the quantified
data awaits further analysis of the data.
CFE ISS
Gallery
Increment
26 flight engineer Cady Coleman operates the CFE-2 Interior Corner
Flow 2 unit.
Astronaut
Peggy A. Whitson, Expedition 16 commander
ISS Science Officer, Mike Fincke
in the U.S. Lab aboard the International Space Station.
Sunita Williams
performing ICF2 ops during Increment 15 on the International Space
Station.
Astronaut
Jeffrey N. Williams, Expedition 13 NASA space station science
officer and flight engineer, performs one of multiple tests of
the Capillary Flow Experiment (CFE) investigation on the
ISS.
